You want to surprise someone with a ring, or order one online, and you don't know the size. Can you really figure it out at home without a jeweler's gauge? Yes, and with a little care you can get within half a size. We've sized thousands of fingers over the years, and the same few mistakes cause most of the wrong-size orders we see.
Start With the Right Moment
Fingers change size through the day. They're smallest first thing in the morning or when you're cold, and they swell after a long walk, a salty meal, or a hot shower. So don't measure once and trust it. Measure at the end of the day when your hands are at a normal temperature, and repeat on a second day. If the two numbers differ, go with the average and lean slightly larger.
Measure the finger the ring will actually live on. Your dominant hand is usually about half a size bigger than the other, and the ring finger is rarely the same as the middle or index finger.
A slim band like the 14K Yellow Gold Double Band Diamond Engagement Ring is forgiving, since it sits lightly and doesn't grip the knuckle.
The String or Paper Method
This is the one we recommend most. Cut a strip of paper or a piece of non-stretchy string about six inches long. Wrap it around the base of your finger, snug but not tight, and mark where the end meets the overlap. Lay it flat against a ruler and read the length in millimeters. That's your circumference. Divide by 3.14 to get the diameter, or simply match it to a size chart: roughly 49 mm is a size 5, 52 mm is a 6, 54 mm is a 7, 57 mm is an 8, and 60 mm is a 9.
Paper has a flaw: it can crease and cut a little short. String is better, but anything with give will stretch and make you think you're smaller. Dental floss works well because it barely stretches. Whatever you use, check that you can still slide it over your knuckle. The knuckle is the whole problem, and we'll come back to it.
Use a Ring That Already Fits
If you own a ring that fits the right finger comfortably, you're nearly done. Measure the inside diameter across the widest point, from one inner edge to the other, in millimeters. A diameter of about 15.7 mm is a size 5, 17.3 mm is a 7, and 19.0 mm is a 9. This works best when the ring is a similar width to the one you plan to buy, which brings up the next point.
Wider or stacked designs such as the 14K Gold Eternity 3-Tier Diamond Ring fill more of the finger, so they tend to feel tighter than a thin band.
Width and Knuckles Change Everything
A wide band covers more skin, so it feels tighter than a thin one in the same size. As a rule, if you're buying a band wider than 6 mm, or a ring with several tiers, go up a quarter to half size. Thin solitaires can stay true to size.
Then there's the knuckle. If yours is much larger than the base of your finger, the ring has to clear the knuckle and then spin loosely once it's in place. Measure both spots and pick a size between them, leaning toward the knuckle. A jeweler can add small sizing beads inside the shank to stop spinning, which is a simple fix and far better than a ring you can't get on.
Detailed settings like the 14K Gold Diamond Baguette Engagement Ring are worth sizing carefully, because resizing a stone-heavy band is harder.
When You Should Still See a Jeweler
For an engagement ring, or any ring with stones set around the band, it's worth getting a free measurement at a local jeweler. A proper sizer set tells you in half a minute and costs nothing. Rings with diamonds all the way around are tough to resize, and sometimes impossible, so it pays to get it right the first time.
If you're gifting and can't ask, borrow a ring she or he wears on the right finger and trace the inside on paper, or compare it to a size chart. Keep our U.S. return window in mind too: orders shipped within the U.S. can be returned within 30 days, so a near miss isn't a disaster. When you're ready, browse our rings collection and measure twice before you buy.